[WebSocket] Fix a crash caused by a pending empty frame.

net/websockets/websocket_channel_test.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/websockets/websocket_channel.h"
 
 #include <limits.h>
 #include <string.h>
 
 #include <iostream>
@@ skipping 2388 matching lines @@
 
 // An empty message handled when we are out of quota must not be delivered
 // out-of-order with respect to other messages.
 TEST_F(WebSocketChannelFlowControlTest, EmptyMessageNoQuota) {
   scoped_ptr<ReadableFakeWebSocketStream> stream(
       new ReadableFakeWebSocketStream);
   static const InitFrame frames[] = {
       {FINAL_FRAME, WebSocketFrameHeader::kOpCodeText,
        NOT_MASKED,  "FIRST MESSAGE"},
       {FINAL_FRAME, WebSocketFrameHeader::kOpCodeText,
-       NOT_MASKED,  ""},
+       NOT_MASKED,  NULL},
       {FINAL_FRAME, WebSocketFrameHeader::kOpCodeText,
        NOT_MASKED,  "THIRD MESSAGE"}};
   stream->PrepareReadFrames(ReadableFakeWebSocketStream::SYNC, OK, frames);
   set_stream(stream.Pass());
   {
     InSequence s;
     EXPECT_CALL(*event_interface_, OnAddChannelResponse(false, _, _));
     EXPECT_CALL(*event_interface_, OnFlowControl(_));
     EXPECT_CALL(*event_interface_,
                 OnDataFrame(false,
@@ skipping 954 matching lines @@
   channel_->StartClosingHandshake(kWebSocketNormalClosure, "OK");
   ASSERT_TRUE(read_frames);
   // Provide the "Close" message from the server.
   *read_frames = CreateFrameVector(frames);
   read_callback.Run(OK);
   completion.WaitForResult();
 }
 
 }  // namespace
 }  // namespace net